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https://issues.apache.org/jira/browse/FLINK-7996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16241732#comment-16241732
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Xingcan Cui commented on FLINK-7996:
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Hi [~fhueske], thanks for opening this. IMO, the conditions like {{left.time =
right.time + C}} should also be valid since they can be transformed to a window
like {{left.time >= right.time + C && left.time <= right.time + C}}. While this
seems to be sort of contradictory with FLINK-7800, in which the row expression
like {{left.attr = right.attr + C}} will always be translated to a calculation
with an equi-join (i.e., $1 = right.time + C and left.time = $1). I need to
consider the two problems as a whole.
Best, Xingcan
> Add support for (left.time = right.time) predicates to window join.
> -------------------------------------------------------------------
>
> Key: FLINK-7996
> URL: https://issues.apache.org/jira/browse/FLINK-7996
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Affects Versions: 1.4.0
> Reporter: Fabian Hueske
> Assignee: Xingcan Cui
> Priority: Critical
> Fix For: 1.4.0
>
>
> A common operation is to join the result of two window aggregations on the
> same timestamp.
> However, window joins do not support equality predicates on time attributes
> such as {{left.time = right.time}} but require two range predicates such as
> {{left.time >= right.time AND left.time <= right.time}}.
> This can be fixed in the translation code (the operator does not have to be
> touched).
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